The invention relates to a multilayer structure comprising at least one plastic film, a crystalline organic barrier layer and a printed pattern. The invention further relates to a process for the preparation thereof.
The invention furthermore relates to a laminate comprising the multilayer structure and a further plastic film.
Plastic films are used in laminates and labels or lids for packaging, electronic and other industries. Often, such films and laminates have decorative characteristics, like printings and/or functional characteristics, like good barrier properties such as low oxygen or water vapor transmission rates.
For improving the barrier properties of laminates, plastic films often are coated with one or more layers. Yet, the adhesion between the outer films needs to be sufficiently high. Laminates are known with on a first side a plastic film, for example polyolefin, polyamide or polyester films, which is coated with a metal or metal oxide, like e.g. aluminum, aluminum oxide, magnesium oxide or silicium oxide. The film with barrier properties is generally laminated with e.g. a further polyolefin film while using an adhesive, or with extrusion lamination. Such laminates can have good barrier properties. However, the metal layers that are used to enhance the barrier properties are non-transparent, cause environmental concern as they consume high amount of energy for deposition, cause difficulties in recycling, and are not micro-waveable. Metal oxide layers that are used to enhance barrier properties are easily damaged, expensive and require high level operators to reliably produce laminates. PVDC type of barrier films cause environmental concerns because of its chlorine content. EVOH type of barrier films are highly moisture sensitive. Crystalline organic barrier, like triazine layers, such as melamine or other organic compounds are known as well (see e.g. WO99/66097 or WO2010/003958). These layers are transparent and recyclable. It appears however, that during processing—like all barrier layers—the barrier properties may become impeded. Thus, an ongoing search for laminates with barrier layers is apparent, in which the laminates have and/or retain good properties.
For lids, shrink wrap labels and the like, the barrier properties are not the primary goal, but printing needs to be of high quality and withstand harsh conditions during the application of lids for example on bottles and subsequent wash steps. This often is difficult on bare film. Hence, primers and the like are used. Yet, improvement with respect to economy of such printing is still searched for.